Seamless in-line airboat muffler

ABSTRACT

A muffler comprising a generally cylindrical in-line muffler having a seamless outer body for use in silencing airboat engines is disclosed. An inner perforated stainless steel inner tube is surrounded by a stainless steel mesh liner and a stainless steel outer body having opposing ends swaged to a reduced diameter. The use of all stainless steel components provides a muffler that is highly resistant to corrosion. In addition, the muffler is ideally suited for use in marine environments since it is capable of discharging ingested water as the stainless steel perforated inner tube and mesh liner will not become water logged. A method for fabricating mufflers in accordance with the present invention if further disclosed.

CROSS REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of provisional U.S. Patent Application Ser. No. 60/995,424, filed Sep. 26, 2007

STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT

N/A

COPYRIGHT NOTICE

A portion of the disclosure of this patent document contains material that is subject to copyright protection. The copyright owner has no objection to the facsimile reproduction by anyone of the patent document or patent disclosure as it appears in the Patent and Trademark Office patent file or records, but otherwise reserves all rights whatsoever.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates generally to mufflers for use with internal combustion engines, and more particularly to a seamless in-line muffler specifically designed for use on an airboat.

2. Description of Related Art

Airboats are a very popular means of transportation in the Florida Everglades where they are used for fishing, hunting and eco-tourism. Airboats are flat-bottomed vessels propelled by an aircraft type propeller powered by either an aircraft or automotive engine. The engine and propeller are enclosed in a protective metal cage that prevents objects, i.e., tree limbs, branches, clothing, beverage containers, wildlife from coming in contact with the whirling propeller, which could cause devastating damage to the vessel and traumatic injury to the operator and passengers. Airboats vary in size from 10 foot hunt/trail boats, with a two to three passenger capacity, to large 18 passenger and greater tour boats.

The propeller produces a rearward column of air that propels the airboat forward. Steering is accomplished by forced air passing across vertical rudders. The characteristic flat-bottomed design of the airboat, in conjunction with the fact that there are no operating parts below the waterline, permit the vessel to be easily navigated through shallow swamps and marshes, in canals, rivers and lakes as well as on frozen lakes.

Airboats are powered by either an aircraft or large block automotive engine, ranging from 125 to over 600 horsepower. An automotive engine powered airboat generally has more power to push through high grass or carry heavy loads. An aircraft engine powered airboat may still be preferred in situations where a light boat or greater maneuverability is desired.

The sound produced by an airboat's propeller and engine can be extremely loud. Attempts are constantly being made to reduce the sound that an airboat produces. For example, some airboat engines are equipped with mufflers and multi-blade carbon-fiber propellers in an attempt to reduce the sound emitted by the airboat.

One difficulty faced by efforts to silence airboat engines involves the need for a compact muffler specifically adapted for use on an airboat wherein the muffler is exposed to often harsh, and wet marine environments. As a result of the harsh operating environment, airboat mufflers must be capable of withstanding corrosion and exposure to water, while further being capable of discharging any water ingested by the engine.

BRIEF SUMMARY OF THE INVENTION

The present invention overcomes the limitations and disadvantages present in the art by providing a compact generally cylindrical in-line muffler having a seamless outer body for use in silencing airboat engines. An airboat muffler in accordance with the present invention includes an inner perforated stainless steel tube, a stainless steel mesh liner tightly wrapped around the inner tube, and a stainless steel outer body having opposing ends swaged to a reduced diameter to secure the internal components. The use of all stainless steel components provides a muffler that is highly resistant to corrosion. In addition, the muffler is ideally suited for use in marine environments since it is capable of discharging ingested water as the stainless steel perforated inner tube and mesh liner will not become water logged. A method for fabricating mufflers in accordance with the present invention if further disclosed.

Accordingly, it is an object of the present invention to provide an improved muffler for use with an internal combustion engine.

Another object of the present invention is to provide such a muffler formed with a seamless outer housing.

Yet another object of the present invention is to provide an airboat muffler having an internal structure that does not retain water.

Still another object of the present invention is to provide an airboat muffler fabricated from all stainless steel parts.

Another object of the present invention is to provide a method for fabricating an airboat muffler as disclosed herein.

In accordance with these and other objects, which will become apparent hereinafter, the instant invention will now be described with particular reference to the accompanying drawings.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

FIG. 1 is a side view of an airboat muffler in accordance with the present invention;

FIG. 2 is a side sectional view thereof;

FIG. 3 is a partial cutaway view thereof; and

FIGS. 4A-4I illustrate the manufacturing steps for fabricating an airboat muffler in accordance with the present invention;

DETAILED DESCRIPTION OF THE INVENTION

With reference now to the drawings, FIGS. 1-3 depict an in-line muffler, generally referenced as 10, having a seamless outer body, for use in silencing airboat engines in accordance with the present invention. Airboat muffler 10 may be fabricated to any suitable dimensional and/or horsepower specifications sufficient to achieve results consistent with the intended objectives disclosed herein.

Airboat muffler 10 includes an inner perforated stainless steel tube 20, a stainless steel mesh liner 30 wrapped tightly around inner tube 20, and an outer tubular stainless steel sleeve 40. In accordance with a preferred embodiment, steel tube 20, liner 30, and a tubular sleeve 40 are all fabricated from stainless steel components to provide a muffler that is highly resistant to corrosion. Stainless steel tube 20 preferably comprises a generally cylindrical tubular member of 18-gauge Stainless steel having a suitable outer diameter (e.g. 2.5″, 3.0″, 3.5″ etc.) and suitable length (e.g. 12″). Stainless steel tube 20 preferably defines a plurality of perforations or apertures to allow exhaust gas to flow through the tube wall.

Stainless steel liner 30 preferably comprises a mesh liner fabricated from 304 stainless steel fibers having an overall thickness of approximately ¼-inch. In a preferred embodiment, liner 30 is comprised of fibers similar to a BRILLO® cleaning pad, however, any suitable mesh configuration is considered within the scope of the present invention. BRILLO® is a registered trademark of Church & Dwight Co., Inc. It is not considered desirable to apply chemicals to, or otherwise coat liner 30 with any substance such that stainless-to-stainless contact is maintained between the muffler components thereby minimizing the introduction of electrolytes that could lead to electrolytic corrosion. Further, the application of foreign substances to liner 30 is believed to increase water retention (e.g. decrease water discharge capability) in the event of water ingestion. Liner 30 is disposed in wrapped surrounding relation with inner tube 20.

Tubular outer sleeve 40 preferably comprises a generally cylindrical tubular member having opposing open end portions, referenced as 42 and 44, disposed in surrounding relation with perforated stainless tube 20, and mesh liner 30 as best illustrated in FIGS. 1 and 2. End portions 42 and 44 are preferably swaged to a reduced diameter relative to the mid-portion of tubular sleeve 40 thereby defining a radially enlarged mid-body portion, referenced as 46, wherein liner 30 is encased and secured. The term swaging refers to a metal-forming technique in which the metal is plastically deformed to a final shape using high pressures, either by pressing or hammering, or by forcing the material through a die. Providing a muffler devoid of seams (e.g. portions were metal is joined by fabrication) is considered a significant aspect of the present invention. The seamless configuration functions particularly well to prevent water intrusion in the aquatic environments wherein airboats operate, as well as providing a significantly superior exterior appearance.

FIGS. 4A-4I illustrate fabrication of airboat muffler 10 in accordance with the present invention. Step 1 illustrates providing a perforated stainless steel inner tube 20. Steps 2 and 3 shown in FIG. 3 illustrate providing a stainless steel mesh liner 30 and installing the liner in tightly wrapped surrounding relation with inner tube 20. Steps 4 and 5 illustrate the use of a spacer block, referenced as 50, to align the tubular outer sleeve 40 relative to mesh liner 30 and inner tube 20. Step 6 illustrates swaging down outer tubular sleeve 40 to form an end portion 42 of reduced radial diameter. Step 7 illustrates swaging down outer tubular sleeve 40 to form an end portion 44 of reduced radial diameter. Steps 8 and 9 illustrate finishing and final marking steps.

An airboat muffler 10 in accordance with the present invention is ideally suited for use in marine environments since it is capable of discharging ingested water as the stainless steel perforated inner tube and mesh liner will not become water logged. Accordingly, the use of a stainless steel mesh is considered a significant aspect of the present invention, namely providing a muffler specifically designed to handle the particular environmental challenges experienced when used with an engine powering an airboat in an aquatic environment. These challenges are made more difficult than, for example inboard marine engines, since airboat engines are often mounted generally exposed to the airboat frame. Exposed mounting renders airboat engines more likely to ingest water. As a result, providing a muffler capable of discharging ingested water is a critical aspect of the present invention.

The instant invention has been shown and described herein in what is considered to be the most practical and preferred embodiment. It is recognized, however, that departures may be made therefrom within the scope of the invention and that obvious modifications will occur to a person skilled in the art. 

1. An exhaust muffler comprising: a perforated tube having a middle portion and opposing end portions; a mesh liner disposed in concentric surrounding relation with said perforated tube middle portion; a tubular sleeve disposed in concentric surrounding relation with said perforated tube and said mesh liner having, said sleeve having an inlet end disposed in proximity to one end of said perforated tube and an outlet end disposed in proximity to the opposing end of said perforated tube; said tubular sleeve having a radially enlarged middle portion generally encasing said mesh liner sandwiched between said an inner surface of said tubular sleeve and an outer surface of said perforated tube, said tubular sleeve swaged to a reduced diameter at opposing ends of said radially enlarged middle portion to provide a seamless outer surface.
 2. An exhaust muffler according to claim 1, wherein said perforated tube is formed of stainless steel.
 3. An exhaust muffler according to claim 1, wherein said mesh liner is formed of stainless steel.
 4. An exhaust muffler according to claim 1, wherein said tubular sleeve formed of stainless steel.
 5. An exhaust muffler for use with an airboat at engine, said exhaust muffler comprising: a stainless steel perforated tube having a middle portion and opposing end portions; a stainless steel mesh liner disposed in concentric surrounding relation with said perforated tube middle portion; a stainless steel tubular sleeve disposed in concentric surrounding relation with said perforated tube and said mesh liner having, said tubular sleeve having an inlet end projecting from one end of said perforated tube and an outlet end projecting from the opposing end of said perforated tube; said tubular sleeve having a radially enlarged middle portion generally encasing said mesh liner sandwiched between said outer body and said perforated tube, said outer body swaged to a reduced diameter at opposing ends of said radially enlarged middle portion so as to be devoid of scams.
 6. An exhaust muffler for use with an airboat engine according to claim 5, wherein said mesh liner comprises stainless steel wool. 